Just some hints …
If you are using 5G wifi on chanels using DFS then it might cause MacOS clients to be disconnected time to time. Aside of that, check if the wifi adapter is not powered down by power management (if that occurs and AP will send ACK and does not get response in time, it will disasociate that client - disconnect it, until it will try to reconnect).
Check this thread: Solution found for WiFi clients disconnects
There are some hints which you can try to set in “wireless” uci (option wpa_group_rekey '86400'
and option disassoc_low_ack '0' worked for me in the way that i have less messages in log related to wifi/client disconnected. If you are not having wpa_group_rekey explicitly specified, default value is used by hostapd (which is 300 if i remember well).
[OpenWrt Wiki] Wi-Fi /etc/config/wireless
If you are using 2,4 and 5g together do not use HT+ /HT- on 2,4 wifi at all, stick with the 20 (even if you use 40 it will probably fallback to 20 anyway as very probably there won’t be free side channels or you are using center channel at the edges of the channel range , so no side-channels are available). If you are having only 2,4 at use you can benefit from HT mode (if you have not so crowded area with AP). On the other hand when you are using 5G you can use VHT40/80/160 as you want.
And basically, you have DHCP lease and “wpa_group_rekey” time values. So not only AP it self might disconnect client, it also kind of ask for new lease and it might cause that client has to reconnect to AP again. If this occurs, i have like 1-5sec with no connection at all and when trying to reconnect to same AP it actually fails (… until, kresd/resolver finish the lease refresh/add lease/remove lease …), I can connect to my other APs as used-to (without any delay).
Also what i’ve notice with my work-laptop (which is usually in vpn and has own domain), that it is almost only client having such issues (other clients do not stay connect over 12h resp 24h).
For some users it helps changing from PSK2+TKIP+AES to PSK2+CCMP.
5G AP can also benefit from those settings: option bursting '1' ; option ff '1' ; option turbo '1' (but check if those applies for you, if those are compatible with your TOS/OpenWRT release ; now i do not see those options in uci/wireless docu on Openwrtwiki [OpenWrt Wiki] Wi-Fi /etc/config/wireless anymore.